By contrast, terrestrial NORM – especially radon – contributes to the majority of natural dose, usually over 1000 microsieverts (1 m Sv) per year.
Some of the main comsogenic nuclides are shown in Table 1, carbon-14 being important for dating early human activities.
The long half-life of K-40 (1.25 billion years) means that it still exists in measurable quantities today.
This means that material which is considered radioactive waste in one context may not be considered so in another.
Also, that which may constitute low-level waste in the nuclear industry might go entirely unregulated in another industry (see section below on recycling and NORM).
Excluding uranium mining and all associated fuel cycle activities, industries known to have NORM issues include: Another NORM issue relates to radon exposure in homes, particularly those built on granitic ground.
Occupational health issues include the exposure of flight crew to higher levels of cosmic radiation, the exposure of tour guides to radon in caves, exposure of miners to radon underground, and exposure of workers in the oil & gas and mineral sands industries to elevated radiation levels in the materials they handle.